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International Journal of Computer

Science and Information Technology International Journal of Computer Science and Information Technology, 2016, 2(1),8-11

T.Chockalingam et al., Page No.8

Temperature based dc fan speed control system using microcontroller and pulse

width modulation technique using PIC16F877A

T.Chockalingam 1,

Melese Yemane1and A.Agasthian

2

1Ambo University, Ambo, Ethiopia

2Network Administrator, Annauniversity, Thoothukudi Campus, India

Jaisree2008@gmail.com

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ABSTARCT: Temperature based dc fan speed control system using microcontroller and pulse width modulation technique

using PIC16F877A is to control the speed of dc fan speed based on room temperature using pulse width modulation technique

with microcontroller. The temperature is read from the temperature feeler and the situation is checked depending on

temperature rate. The aim of developing this project is to control the speed of DC fan motor. The main advantage in using a DC

fan motor is that the s p e e d -Torque relationship can be varied to almost any useful form. To achieve the speed control an

electronic technique called Pulse Width Modulation is used which generates High and Low pulses. These pulses vary the speed

in the motor. For the generation of these pulses a microcontroller (PIC 16F877A) is used. As a microcontroller is used setting

the speed ranges as per the condition is easy which is done by changing the duty cycles time period in the program. This project

is practical and highly feasible in economic point of view, and has an advantage of running motors of higher ratings. This

project gives a reliable, strong, exact and efficient way of speed control of a DC fan motor. The simulation of the system has

been done on Proteus Professional Software v 8.1. Hardware implementation has been also done. The results of the research

and Output waveforms have been investigated.

Keywords: Microcontroller, temperature sensor, analog to digital converter, DC Fan, pulse width modulation and speed

control.

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1. Introduction

The aim of this project is to control the speed of dc

fan speed based on temperature using pulse width modulation

technique with microcontroller. To get rid of the problem of

Obscurity to control temperature in industries, public

building, apartment house and private house a

microcontroller based controller has been proposed.

A temperature sensor has been used to measure the

temperature of the room and the speed of the fan is varied

according to the room temperature using pulse width

modulation technique. Controller is used to control the speed

of DC Fan and temperature is varied through the

Temperature sensor and data is sent to PIC 16F877A

microcontroller using analog to digital converter. The duty

cycle has been varied from 0 to 100% to control the fan

speed depending up on the room temperature, which is

displayed on liquid crystal display. Duty cycle values

between 20% and 90% allow smooth control of the fan.

Out of various control techniques available only two of them

can be used to control DC motor. They are sensor control and

sensor less control. With the improvement in machinery,

smart systems are being introduced every day. In the present

time microcontrollers play a vital role in the development of

the smart systems.

It is to be noted that dc motor is not directly

connected with microcontroller because a micro controller

can’t supply the current for the working of DC motor.

An independent control system which responses on the

ambience conditions. The idea behind this project is to

control the speed of DC fan using microcontroller based on

variation in temperature. Temperature controlled fan is an

alternative way to deal with the speed of the motor.

Temperature control is a process in which the

temperature of an object is measured and the passage of heat

energy into or out of the object is adjusted to achieve a

desired temperature. This project presents the interfacing of

temperature sensor with microcontroller by means of analog

to digital convertor, to display the temperature on a 16x2

LCD and to rotate a DC motor at different speeds at various

temperatures.

The pulse width modulation speed control function

is a function that externally controls the rotation speed of the

fan by changing the duty cycle of the input pulse signal

between the control terminal and GND.

Figure1.1 block diagram

International Journal of Computer Science and Information Technology, 2016, 2(1),8-11

T.Chockalingam et al., Page No.9

2. PROBLEM STATMENT

Statement of Problem

As the system is microprocessor based system, it has more

automated control over different operations. So it reduces the

communication of human with the system for those

operations such as controlling a fan for room temperature

.This project helps the user of the library to have a moderate

environment inside the library with a room temperature.

2.1 Objective

The objective of these project can be seen in two direction

based on main and supportive application of our design.

2.2 General Objective

The main aim of this document is to save energy

through the projected method. The power

consumption is reduced.

To control temperature variation using dc fan speed

control system.

2.3 Specific Objective

It is creation the library stylish by controlling,

temperature using a single microcontroller.

To solve a room temperature problem and find the

way to simplifies people’s life safety

To controls the rotation speed of the fan by

changing the duty cycle of the input pulse signal.

3. Methodology

The methodology we have followed during the development

of this project which starts from project title selection up to

the complete project submission is presented in this section.

First we did appropriately select the project title. After a

topic has been selected, additional discussions were done in

order to understand the concept and objective of the project.

Then, literature review was done and the background of this

project was studied by referring to various sources such as

reference books, internet, lecture notes and data sheets.

Figure 3.1 the Work Flow of the Project

In this project we have to analysis, design, select an

optimum or suitable materials and simulation of temperature

based dc fan speed control using microcontroller and pulse

width modulation technique. Firstly, Chips would be made to

be installed on the dc fan speed control system. These chips

will consist of a micro-controller along with temperature

sensors.

Figure 2.1 showed the methodology or work flow

for the project which is involving system development from

hardware and software to the integration of both elements.

Then, the system is being tested to produce a certain results

that will be analyzed to produce the results that compatible

with the system.

3.1.HARDWARE BLOCK DIAGRAM

Figure 3.2 Block Diagram of Simple System Design for a

temperature based dc Fan System

3.2 IMPLEMENTATION

1. The output pin of LM35 temperature sensor was connected

to one of the ADC input pin of PIC16F877A microcontroller.

2. LCD was connected to the microcontroller.

3. ADC was activated for interfacing the temperature sensor

and a program is written so that whatever temperature the

sensor senses it can be displayed on LCD screen.

4. Either electric AC bulb or soldering iron is used to heat the

temperature sensor.

5. Electric motor driver L293D is connected to

microcontroller.

6. DC motor is connected to the output of motor driver pin.

3.3 Schematic Diagram

Figure3.3 Schematic diagram

International Journal of Computer Science and Information Technology, 2016, 2(1),8-11

T.Chockalingam et al., Page No.10

Figure 3.4 flow chart

4. WORKING PRINCIPLE

The project uses a accuracy centigrade temperature sensor

LM35 which is capable of sensing the temperature. It gives

the output in mill volts. This output is converted into

corresponding digit data using inbuilt ADC of the PIC 16F

877A microcontroller. LCD is interfaced with the

microcontroller & the value of the actual temperature is

displayed on the LCD. The LCD displays the present

temperature. Also speed of the DC motor either increased or

decreased depends on the input temperature. The electric

soldering iron or electric bulb is used to differ the input

temperature.

5. Software procedures

The following software’s were used for programming and

feeding in PIC16f877A

1. Proteus 8.1 used to simulate the schematic diagram and

check the performance.

2. CCS compiler used to compile the program and generate

the Hex code.

6. HARDWARE OF THE PROJECT

Figure 6.1 Hardware Implementation

7.Discussion on Result

The speed of the fan has been controlled using PWM

technique according to the room temperature. The simulation

of the system has been done on Proteus Professional v 8.0

software packages and it is running in good agreement. The

logic used in the system is verified and shown in the

flowchart form. The duty cycle has been varied according to

room temperature and speed of the fan was controlled

accordingly. The accuracy of the system was validated. The

design of the system presented in this paper is appropriate

according to the modern technology.

TEMP AT 310C

As Figure bellow shows Pulse for temperature at 31℃. There

is variation in pulse at the same time fan speed is slow

Figure7.1 Pulse for temperature at31 ℃

TEMP 370C

TEMP 49

0C

TEMP 80

0C

International Journal of Computer Science and Information Technology, 2016, 2(1),8-11

T.Chockalingam et al., Page No.11

TEMP 100

0C

8.RESULTS AND CONCLUSION

8.1 Results

The project “Temperature based DC Fan Speed Control

System using Microcontroller and Pulse Width Modulation

Technique using PIC 16F877A” has been successfully

designed and tested. It is fairly clear from the above

argument that Speed Control of DC fan motor using

microcontroller by using PWM may be a complete system

that controls the speed of a motor by giving instructions to

the microcontroller to reduce the manual effort. The

technology saves money too and gives a return on

investment. This system have a great deal in common with

one another, 12V is used in this process of speed control of

dc motor. Execution of this process is easy. So by using

micro controller we control the speed of a DC fan motor

using L293D Motor driver IC. By applying a PWM pulse to

L293D, the speed of the motor varies .We used an LCD for

displaying the varying temperature. If we change the

temperature in Lm35 by either heater or bulb microcontroller

varies the duty cycle of the PWM accordingly so that the

average power will vary resulting variations in the speed.

8.2 Conclusion

The simulation of the system is working properly and the

design is appropriate according to the modern needs and

technology. The speed of fan depends on temperature and

there is no need for regulating the speed manually. Various

graphs have been plotted to show the varying relationships

between different parameters. PWM technique is found to be

appropriate for controlling fan speed according to room

temperature. After comparing duty cycle and speed of DC

Fan according to temperature variation in software and

hardware we have observed approximately same result.

This design can be further extended in terms of area and

power at layout and characteristic level by using Advanced

VLSI applications. Finally we conclude that this method is

one of the best methods for controlling the speed of the DC

fan motor.

REFERENCES

1. PIC 16F87X A data sheet

2. LM 35 temperature sensor data sheet. http:// www.ti.com

3. L293d Motor driver data sheet

4. LCD016L data sheet.

5. Vaibhav Bhatia and Gavish, International Journal of

Computer Applications (0975 – 8887) Volume 81 – No5,

November 2013

6. R.Krishnan, “Electric Motor Drives Modelling, Analysis,

and Control, Prentice Hall International Inc., New Jersey,

2001.

7. F. Luo, X. Zhao, and Y. Xu, "A new hybrid elevator

group control system scheduling strategy based on

particle swarm simulated annealing optimization

algorithm", Intelligent Control and Automation

(WCICA), 5121-5124, 2010.

8. Fundamentals of electric drive by Gopal k dubey”, narosa

publishing house New Delhi,1989

9. A. Z. Ahmad and M. N. Taib, A study On the DC Motor

Speed Control by Using Back-EMF Voltage, Asia

SENSE SENSOR, 359-364, 2003.

10. I. John, PIC Microcontroller Project Book, second ed.,

Mc Graw-Hill, Singapore, 2000.

11. Xiaodong Xia, Coal Mine Machinery, 202- 204, 32 (8),

2011.

12. J. Vig and A. Ballato, “Ultrasonic Instruments and

Devices”, Academic Press Inc. pp. 637 -701 (Chapter7:

Frequency Control Devices). 1999